i am able to R/W a single byte but how do i R/W multiple

[sonic91]

i have finally figured out how to read to a text box and write back to the file but i can only do it a byte at a time
this is my read and write code

private void btnRead_Click(object sender, EventArgs e)
        {
            
            fs = File.Open(ofd.FileName, FileMode.Open, FileAccess.Read);
            BinaryReader br = new BinaryReader(fs);
            br.BaseStream.Seek(0x83, SeekOrigin.Begin);
            byte b = br.ReadByte();
            br.Close();
            textBox1.Text = b.ToString("X2"); // display in hex
        }
private void btnwrite_Click(object sender, EventArgs e)
        {
            byte b = Convert.ToByte(textBox1.Text, 16);
            fs = File.Open(ofd.FileName, FileMode.Open, FileAccess.Write);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Seek(0x83, SeekOrigin.Begin);
            bw.Write(b);
            bw.Close();
        }

but i need this to read and write from offset 0x83 to 0x8f i also need to do this read and write with ancii for the same length just a different area but i dont know where to start with that.


Please help its making me go gray :(